<?php
session_start();
//check if user if signed in
if (isset($_SESSION['signed_in']) && $_SESSION['signed_in'] == true) {
	//unset all variables
	$_SESSION['signed_in'] = NULL;
	$_SESSION['user_name'] = NULL;
	$_SESSION['user_id'] = NULL;
}

header('Location: index.php?string=logout');
?>